Have a Rem 700 Barrel, looking for advice

I've acquired a 24" Remington 700 7mm SAUM stainless barrel and was thinking about doing a build that was going to be cost effective. I just wanted a good lightweight rifle to back up my 700 264 win mag or vice versa. Is it feesable to complete this rifle for 600 dollars or less? What's a gunsmith charge just to switch barrels and headspace? I just can't justify spending more than what I could buy a 7mm SAUM for complete so I'm thinking about scrapping the idea.